Despite tremendous effort in the field, no single compound or alloy has yet been discovered which possesses all of the desired characteristics for an ideal permanent magnet. Desirable characteristics include high magnetization, high Curie temperature, high magnetocrystalline anisotropy, and low cost. Samarium-cobalt intermetallic compounds (including SmCo5, Sm2Co7, and Sm2Co17) have the highest magnetocrystalline anisotropy (up to 107 erg/cm3) and the highest Curie temperatures (up to 1190K) among all hard magnetic phases discovered to date. However, currently available Sm—Co based magnets have relatively low saturation magnetization (Ms) compared to Nd—Fe based magnets, which has restricted their utilization in high power density applications such as wind power turbines and the electric motors in hybrid vehicles. But Nd—Fe based magnets are not ideal for high power density applications either. Because Nd—Fe based magnets have considerably lower Curie temperatures (580K), their use in high power density applications requires cooling, thus reducing the overall system efficiency. It is therefore desirable to provide a new type of permanent magnet that can function in high power density applications at high operating temperatures without cooling.
One metric for measuring a magnetic material's usefulness as a permanent magnet in some applications is the so called energy product, which is the maximum value of B times H that can be obtained from a given demagnetization curve (or demagnetizing quadrant in a hysteresis curve), where B is magnetic induction and H is magnetic field strength. The energy product can thus be denoted as (BH)max. For many applications, including high power density applications, it is desirable to provide magnets having a high energy product. Assuming a constant coercivity, increasing a material's saturation magnetization increases the material's energy product as well.